Polishing method and polishing pad

ABSTRACT

A polishing method includes polishing a surface to be polished of a target object by using a polishing pad in which a cutout part been formed by cutting out a polishing surface from an outer circumferential end toward an inner part, and after polishing, separating the target object from the polishing pad at a position in contact with the cutout part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority Japanese Patent Application No. 2006-198895 filed on Jul. 21, 2006 in Japan, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing method and polishing pad, and for example, a polishing method for polishing a copper (Cu) film, silicon oxide film and the like in a process of a method of manufacturing a semiconductor device and a polishing pad used therefor.

2. Related Art

With increasing integration and higher performance of semiconductor integrated circuits (LSI) in recent years, new micro processing technologies have been developed. Particularly, there have been moves recently to change a wiring material from conventional aluminum (Al) alloys to copper (Cu) or Cu allows (hereinafter called Cu together) having lower resistance to make LSI operate faster. It is difficult to apply a dry etching method, which is frequently used for forming Al alloy wires, to Cu for micro processing. For this reason, a damascene method is mainly adopted for Cu, in which a Cu film is deposited on a dielectric film to which groove machining has been provided and then the Cu film is removed except that in portions where embedded in a groove by chemical-mechanical polishing (CMP) to form embedded wiring. After forming a thin seed layer by a sputtering method or the like, the Cu film is generally formed into a laminated film having a thickness of several hundred nanometers by electrolytic plating. Further, when multi-layer Cu wiring is formed, particularly a method of forming wiring called a dual damascene structure can also be used. In this method, a dielectric film is deposited on lower layer wiring and predetermined via holes and trenches (wiring groove) for upper layer wiring are formed. Then, Cu to be a wiring material is embedded in the via holes and trenches simultaneously, and further unnecessary Cu in the upper layer is removed by CMP for flattening to form embedded wiring.

Recently, the use of a low dielectric constant material film with low relative dielectric constant (low-k film) has also been examined as an interlayer dielectric film. That is, an attempt has been made to reduce parasitic capacitance between wires by using a low-k film whose relative dielectric constant k is, for example, 3.5 or lower instead of a silicon oxide (SiO₂ film) whose relative dielectric constant k is about 4.2. Moreover, a barrier metal film of tantalum (Ta) or the like is generally formed between the Cu film and the low-k film to prevent diffusion of Cu to the low-k film. Then, unnecessary portions of such a barrier metal film are also removed by CMP for flattening. In addition, unnecessary portions of the SiO₂ film are removed by CMP for flattening.

The CMP method is, as described above, a technology widely used in processes of manufacturing semiconductor devices such as high-performance LSI and memory. In the CMP method, a wafer is polished while pressing a surface to be polished of the wafer against a rotating polishing pad (also called polishing cloth) having an approximately circular polishing surface. Here, when separating a wafer after being polished from the polishing pad, the wafer is conventionally caused to move from a polishing position to an outer circumference of the polishing pad by performing an overhang operation and to separate at a position where a portion of the wafer protrudes from the polishing pad. A purpose of performing this operation is to reliably separate the wafer after being polished from the polishing pad despite increased adsorption power between the wafer and the polishing pad due to polishing. On the other hand, an operation to add an extra swing distance to the wafer from the polishing position may be needed.

As a technology related to separation of a wafer from a polishing pad, methods of drilling a through-hole in a polishing pad and feeding compressed air from the polishing pad side to the wafer side have been disclosed (See, for example, Published Unexamined Japanese Patent Application No. 11-114810 (JP-A-11-114810) and Published Unexamined Japanese Patent Application No. 09-85617 (JP-A-09-85617)). However, in such a case, mechanisms for separating a wafer from a polishing pad become complicated, which may lead to increasing manufacturing costs and equipment investment costs. Further, a technology to provide a groove with a grid-like or concentric bottom in a polishing pad to store slurry has been disclosed regardless of separation of a wafer from a polishing pad (See, for example, Published Unexamined Japanese Patent Application No. 2000-755 (JP-A-2000-755)) has been disclosed. However, the technology provides nothing to simplify an operation to separate a wafer.

BRIEF SUMMARY OF THE INVENTION

A polishing method according to an embodiment of the present invention includes polishing a surface to be polished of a target object by using a polishing pad in which a cutout part been formed by cutting out a polishing surface from an outer circumferential end toward an inner part; and after polishing, separating the target object from the polishing pad at a position in contact with the cutout part.

A polishing method according to another embodiment of the present invention includes polishing a surface to be polished of a target object by using a polishing pad in which a cutout part been formed by cutting out a polishing surface from an outer circumferential end toward an inner part, after polishing, moving the target object to a position where a contact area between the target object and the polishing pad becomes smaller based on the cutout part formed in the polishing pad, and after moving, separating the target object from the polishing pad.

A polishing pad according to still another embodiment of the present invention includes a polishing surface for polishing a target object, and an outer circumferential side surface in which a plurality of cutout parts been formed from an outer circumferential end of the polishing surface toward an inner part to be cut through from the polishing surface to a back surface of the polishing surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing a main portion of a polishing method in a first embodiment;

FIG. 2 is a view exemplifying a sectional configuration of a semiconductor device before polishing in the first embodiment;

FIG. 3 is a view exemplifying a sectional configuration of the semiconductor device after polishing in the first embodiment;

FIG. 4 is a conceptual view showing the configuration of a CMP device;

FIG. 5 is a conceptual view for illustrating operations of the CMP device when the CMP device in FIG. 4 is viewed from above;

FIG. 6 is a conceptual view showing the sectional configuration of the CMP device in FIG. 4;

FIG. 7 is a view exemplifying a polishing pad in the first embodiment;

FIGS. 8A and 8B are views for illustrating movement of a substrate in the first embodiment in comparison with that of a conventional one;

FIGS. 9A and 9B are views for illustrating a cross section at a position after the movement of the substrate in the first embodiment in comparison with that of the conventional one;

FIGS. 10A and 10B are views for illustrating dust adhering to the substrate in the first embodiment in comparison with that of the conventional one;

FIG. 11 is a view showing an example of an outer circumferential part of the polishing pad in the first embodiment;

FIG. 12 is a view showing another example of the outer circumferential part of the polishing pad in the first embodiment;

FIG. 13 is a view showing another example of the outer circumferential part of the polishing pad in the first embodiment;

FIG. 14 is a view showing an example of a sectional structure of the outer circumferential part of the polishing pad in the first embodiment;

FIG. 15 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment;

FIG. 16 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment; and

FIG. 17 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

In a first embodiment, description will be given to a polishing pad that can easily perform an operation of separating a wafer or the like after being polished and a polishing method. The first embodiment will be described below with reference to drawings.

FIG. 1 is a flow chart showing a main portion of the polishing method in the first embodiment. In FIG. 1, a series of steps are performed in the present embodiment. The series of steps include a polishing step (S102) of polishing a substrate, a movement step (S104) of moving the substrate to a separation position, and a separation step (S106) of separating the substrate.

FIG. 2 is a view exemplifying a sectional configuration of a semiconductor device before polishing in the first embodiment. In the first embodiment, a case in which a Cu film is polished to form a damascene wire will be described as an example. As shown in FIG. 2, an SiC film 212 to be a ground dielectric film is formed on a substrate 200 as a ground film formation step by depositing, for example, a thin film of a silicon carbide (SiC) film having a thickness of 50 nm by a CVD method. Although the film is formed here by the CVD method, any other method may also be used. Here, for example, a silicon wafer of 300 mm in diameter is used as the substrate 200. Although not shown, a device part or a plug layer may be formed on the surface of the substrate 200. Alternatively, other layers such as a wiring layer may also be formed.

Then, as a low-k film formation step, a thin film of a low-k film 220 using porous low dielectric constant insulating material is formed on a substrate 200 having a thickness of, for example, 200 nm. Forming the low-k film 220 enables to obtain an interlayer dielectric film whose relative dielectric constant k is less than 3.5. Here, the low-k film 220 is formed, as an example, using LKD (Low-K Dielectric material manufactured by JSR) in which polymethyl siloxane that could become a low dielectric constant insulating material of relative dielectric constant of less than 2.5 is used. In addition to polymethyl siloxane, the low-k film 220 may also be formed by using at least one selected from the group consisting of a film having a siloxane backbone structures such as polysiloxane, hydrogen silsesquioxane, and methyl silsesquioxane, a film having as its main component an organic resin such as polyarylene ether, polybenzo-oxazole, and polybenzo-cyclobutene, and a porous film such as a porous silica film. Such a material for the low-k film 220 may have low dielectric constant whose relative dielectric constant is less than 2.5. An SOD (spin on dielectric coating) method can be used, for example, as a formation method in which a thin film is formed by spin-coating and heat-treating a solution. For example, the low-k film 220 can be formed by forming a film by a spinner, baking the film as a wafer on a hot plate in a nitrogen atmosphere, and finally curing the wafer at temperature higher than the baking temperature in the nitrogen atmosphere on the hot plate. By appropriately adjusting the low-k material and formation conditions, a porous dielectric film having predetermined physical property values can be obtained.

As a cap film formation step, a thin film of an SiOC film 222 is formed by depositing carbonation silicon (SiOC) having a thickness of, for example, 50 nm on the low-k film 220 as a cap dielectric film by the CVD method. By forming the SiOC film 222, patterns can be formed on the low-k film 220 while protecting the low-k film 220 on which it is difficult to perform lithography directly. In addition to SiOC, a cap dielectric film may also be formed by using at least one insulating material whose relative dielectric constant is 2.5 or more from the group consisting of TEOS (tetraethoxy silane), silicon carbide (SiC), silicon carbohydrate (SiCH), silicon carbo-nitride (SiCN), SiOCH and silane (SiH₄). The cap dielectric film is formed here by the CVD method, but any other method may also be used.

Next, as an opening formation step, an opening, which is a wiring groove structure for preparing damascene wiring in a lithography step and a dry etching step, is formed inside the SiOC film 222, low-k film 220 and ground SiC film 212. The substrate 200 has a resist film formed on the SiOC film 222 through the lithography step such as a resist application step and exposure step (not shown). The exposed SiOC film 222 and the low-k film 220 positioned thereunder are removed using an anisotropic etching method using the ground SiC film 212 as an etching stopper before forming an opening by performing etching of the ground SiC film 212. Using the anisotropic etching method enables the opening to be formed approximately perpendicularly to the surface of the substrate 200. For example, the opening may be formed by a reactive ions etching method.

Then, as a barrier metal film formation step, a barrier metal film 240 using a barrier metal material is formed in the opening for wiring or to be a contact/via groove formed in the opening formation step and on the surface of the SiOC film 222. The barrier metal film 240 is formed by depositing a thin film of tantalum (Ta) with a thickness of, for example, 5 nm in a sputtering device using a sputtering method, which is one kind of physical vapor deposition (PVD) methods. The method of depositing the barrier metal material is not limited to the PVD process, and also an atomic layer vapor deposition (atomic layer deposition (ALD) method or atomic layer chemical vapor deposition (ALCVD) method) and the CVD method may be used. By using these methods, better coverage can be obtained than when the PVD process is used. Examples of the material for the barrier metal film include not only Ta but also tantalum nitride (TaN), titanium (Ti), tungsten (W), titanium nitride (TiN), tungsten nitride (WN), or a laminated film combining Ta and TaN or others.

Then, as a seed film formation step, a Cu thin film to be a cathode electrode of the next step, an electro-plating step, is deposited (formed) on the opening inner wall where the barrier metal film 240 is formed and substrate surface as a seed film by means of a physical vapor deposition (PVD) method such as sputtering. Here, the seed film with a thickness of, for example, 50 nm is deposited.

Then, as a plating step, a thin film of a Cu film 260 is deposited in the opening and on the substrate surface by an electrochemical deposition process such as electro-plating with the seed film acting as a cathode electrode. Here, after depositing the Cu film 260 having a thickness of, for example, 800 nm, annealing process is performed at 250° C. for 30 minutes. A target object as shown in FIG. 2 obtained by polishing through the process of manufacturing the semiconductor device described above should be prepared.

FIG. 3 is a view exemplifying a sectional configuration of the semiconductor device after polishing in the first embodiment. As the polishing step denoted by S102 in FIG. 1, the surface of the substrate 200 is polished by the CMP process to remove the Cu film 260 including the seed layer and the barrier metal film 240 to be a wiring layer as a conductive part deposited on the surface of the SiOC film 222 excluding a portion of the opening for planarization, to form an embedded structure to be Cu wiring shown in FIG. 3.

FIG. 4 is a conceptual view showing the configuration of a CMP device. FIG. 5 is a conceptual view for illustrating operations of the CMP device when the CMP device in FIG. 4 is viewed from above. In a rotary CMP device to be an example of the polishing device in FIG. 4, a substrate 300 with its surface to be polished directed downward is retained by a top ring 510 on a polishing pad (polishing cloth) 525 arranged on a turn table 520. Pure water supplied from a supply nozzle (not shown) is made to flow over the polishing pad 525, and then, a polishing liquid 540 such as slurry is supplied from a supply nozzle 530. After completing the polishing step using the polishing liquid 540, the polishing liquid 540 over the polishing pad 525 is made to flow by pure water supplied from the supply nozzle (not shown) for substitution. As shown in FIG. 5, by rotating the top ring 510, the substrate 300 is rotated and in turn the turn table 520 is rotated. As the turn table 520 rotates, the polishing pad 525 also rotates. The polishing liquid 540 is supplied to a front position (position denoted by numeral 540 in FIG. 5) of the substrate 300 located in a rotating direction of the polishing pad 525, whereby the polishing liquid 540 is supplied on to the surface of the substrate 300. Here, a polishing pad in which a recess 102 been cut out to act as a cutout part in an outer circumferential part from an outer circumferential end toward an inner part is used as the polishing pad 525.

FIG. 6 is a conceptual view showing the sectional configuration of the CMP device in FIG. 4. While rotating the turn table 520 to which the polishing pad 525 is pasted at, for example, 100 min⁻¹ (rpm), the substrate 300 is brought into contact with the polishing pad 525 by the top ring 510 retaining the substrate 300 with a polishing load P of, for example, 1.96×10⁴ Pa (200 gf/cm²). The number of rotations of the top ring 510 is set, for example, to 105 min⁻¹ (rpm) and the polishing liquid 540 is supplied over the polishing pad 525 from the supply nozzle 530 at a flow rate of 0.2 L/min (200 cc/min). As the polishing pad 525, IC1000 (RODEL Co.), for example, is used.

Polishing of the Cu film 260 has been described in the above description. When polishing an oxide film, for example, polishing may be performed under the following conditions. Slurry to be used is DLS-2 (manufactured by Hitachi Chemical Co. Ltd.) and TK-75 (manufactured by Kao Corporation) is used as a dispersing agent to be added thereto. FREX (manufactured by Ebara Corporation) is used as a polishing device. The polishing conditions in this case are, for example: polishing load (DF): 3.92×1 Pa (400 gf/cm²); the number of rotations of top ring (TR) : 107 min⁻¹ (rpm); the number of rotations of turn table (TT): 100 min⁻¹ (rpm); flow rate of slurry: 0.19 L/min (190 cc/min); and flow rate of dispersing agent: 0.007 L/min (7.0 cc/min). As the polishing pad 525, IC1000 (RODEL Co.), for example, is used. Polishing is performed for 300 seconds under the conditions described above.

FIG. 7 is a view exemplifying a polishing pad in the first embodiment. In the polishing pad 525 shown in FIG. 7, the recess 102 to be a cutout part is formed on an outer circumferential side 20. The recess 102 is formed by cutting out a polishing surface 10 from the outer circumferential end toward the inner part of the polishing surface 10 in an approximately circular form that polishes a substrate surface to be a target object. The recess 102 is formed outside a polishing region 110 where the substrate is actually polished. Then, a plurality of recesses 102 are formed regularly by repeating the recess 102 and a protrusion 104 with a predetermined width W in a predetermined pitch Pt. Here, the recess 102 has a structure cutting through from the polishing surface to a back surface of the polishing surface.

Next, as a movement step denoted by S104 in FIG. 1, the substrate 300 to be a target object is moved after being polished from a polishing position up to a position in contact with the recess 102 by sliding on the polishing surface. FIGS. 8A and 8B are views for illustrating movement of a substrate in the first embodiment in comparison with that of a conventional one. As shown in FIG. 8A, the substrate 300 is conventionally moved till a portion (protruding portion) of the substrate 300 protrudes outside from the outer circumferential end of a polishing pad 625. It is necessary to reduce an adsorption area to reduce adsorption power between the substrate 300 and the polishing pad 625 caused by the polishing step by exposing a portion of the surface to be polished of the substrate 300 to external air. When using a conventional pad, the surface to be polished of the substrate 300 cannot be exposed to external air till the substrate 300 is moved outside the outer circumferential end of the polishing pad 625. In contrast, in the first embodiment, by moving the substrate 300 from the polishing position to a position in contact with the recess 102, as shown in FIG. 8B, an area overlapping with the recess 102 is exposed to external air and adsorption power for that area can be reduced. That is, since the substrate 300 is moved to a position inside the outer circumferential end of the polishing pad 525, a moving distance can be reduced compared with a conventional pad, which makes easy the operation of separating the substrate 300 from the polishing pad 525 of the substrate 300. Also, for a portion of reduced distance, dust adhesion and scratches caused by sliding the substrate 300 on the polishing pad 525 can be reduced.

FIGS. 9A and 9B are views for illustrating a cross section at a position after the movement of the substrate in the first embodiment in comparison with that of the conventional one. If, as conventionally the case, the polishing pad 625 is moved till the substrate 300 protrudes from the outer circumferential end of the polishing pad 625, the polishing pad 625 supporting the polishing load P from the top ring 510 from below (from the opposite side of the load direction) does not exist for a protruding portion of the substrate 300, as shown in FIG. 9A. Thus, the substrate 300 warps with position Q (a line along a trajectory of the outer circumferential end of the polishing pad 625, although shown as a point in FIG. 9A) acting as a fulcrum. As a result, a pressing balance of the substrate 300 is lost, thereby increasing load on point (or line) Q. In contrast, in the first embodiment, the protrusion 104 supports the substrate 300, as shown in FIG. 9B, even if a portion of the substrate 300 is in contact with the recess 102 (overlapping when viewed from above) and thus the substrate 300 is more resistant to bending.

Then, as a separation step denoted by S106 in FIG. 1, the substrate 300 having less contact area with the polishing pad 525 by moving the substrate 300 to a position in contact with the recess 102 is separated at that position upward from the polishing pad 525.

As described above, after the substrate 300 is swung to a position where the substrate 300 is in contact with the polishing pad 525 in a movement operation after polishing, the substrate 300 is separated. The surface of the substrate polished in this way is then inspected for defects to examine the number of defects and distribution thereof. An apparatus for defect inspection manufactured by KLA-Tencor Corporation is used. FIGS. 10A and 10B are views for illustrating dust adhering to the substrate in the first embodiment in comparison with that of the conventional one. In conventional polishing, distribution of defects after polishing is not uniform and biased. This is because the substrate 300 is in contact with the end of the polishing pad 625 during overhang, thereby causing non-uniform load on the substrate 300. That is, if, as conventionally the case, the substrate 300 is separated after moving the substrate 300 to a position where the substrate 300 protrudes from the outer circumferential end of the pad 625, dust 101 concentrates and adheres to a region corresponding to a position denoted by Q as shown in FIG. 10A.

In contrast, in the polishing pad 525 of the first embodiment, the substrate 300 is separated from the polishing pad 525 while inside the polishing pad 525 and thus the end of the polishing pad 625 will not come into contact with the substrate 300. Since the contact area between the substrate 300 and the polishing pad 525 can be reduced by the recess 102 (groove processed part), the substrate 300 can be separated reliably. That is, if the substrate 300 is separated after moving the substrate 300 to a position in contact with the recess 102 while keeping inside the outer circumferential end like in the first embodiment, a region where dust concentrates and adheres can be eliminated or reduced as shown in FIG. 10B.

FIG. 11 is a view showing an example of the outer circumferential part of the polishing pad in the first embodiment. The recess 102 shown in FIG. 7 has a shape, when viewed from the side of polishing surface like a recess 102 a and a protrusion 104 a shown in FIG. 11, formed by cutting the polishing pad 525 from the outer circumferential end toward the inner part in a straight line and a cutout bottom also is formed by a straight line, producing the recess 102 a. However, the shape of the recess 102 is not limited to this.

FIG. 12 is a view showing another example of the outer circumferential part of the polishing pad in the first embodiment. When viewed from the side of the polishing surface like a recess 102 b and a protrusion 104 b shown in FIG. 12, the recess 102 b may also be suitably formed by cutting the polishing pad 525 from the outer circumferential end toward the inner part in a straight line with the cutout bottom being formed by a semicircle or a gentle curve.

FIG. 13 is a view showing another example of the outer circumferential part of the polishing pad in the first embodiment. When viewed from the side of the polishing surface like a recess 102 c and a protrusion 104 c shown in FIG. 13, the recess 102 c may also be suitably formed by cutting out the polishing pad 525 from the outer circumferential end toward the inner part in a form of semicircle or gentle curve.

FIG. 14 is a view showing an example of a sectional structure of the outer circumferential part of the polishing pad in the first embodiment. As shown in FIG. 14, the recess 102 shown in FIG. 7 has a shape cutting through from the polishing surface to the back surface as shown in FIG. 14. By cutting through the polishing pad 525, the substrate surface can be exposed to external air, even if a polishing liquid such as slurry flows in, by draining out such a polishing liquid. The substrate stuck to the polishing pad 525 can be easily separated by exposing the substrate surface to external air. However, the shape of the recess 102 is not limited to this.

FIG. 15 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment. As shown in FIG. 15, the recess 102 may also have a groove shape having a bottom open halfway from the polishing surface toward the back surface. Although more susceptible to an influence of slurry and the like than the shape shown in FIG. 14, the substrate surface can be exposed to external air even in this shape.

FIG. 16 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment. As shown in FIG. 16, the corner between the polishing surface and the side surface of the recess 102 may also be suitably formed like an R-shaped curve. Processing like an R-shaped curve enables to reduce load concentration at the corner when the pressed substrate 300 moves to the outer circumferential end, as compared with right-angle processing.

FIG. 17 is a view showing another example of the sectional structure of the outer circumferential part of the polishing pad in the first embodiment. Alternatively, as shown in FIG. 17, the corner between the polishing surface and the side surface of the recess 102 may also be suitably formed as a plane. Providing chamfering makes it possible to reduce load concentration at the corner when the pressed substrate 300 moves to the outer circumferential end, as compared with right-angle processing.

Here, the width W of the protrusion 104 shown in FIG. 7 is preferably narrow to reduce the contact area with the substrate 300. It is sufficient that the width W and the pitch Pt are so wide as to support the substrate 300 without being bent when the substrate 300 overlaps with the recess 102. It is also preferable to arrange the recess 102 such that the substrate 300 always overlaps with one of the recesses 102 when the substrate 300 is moved to the separation position.

Depth d of cutout shown in FIG. 7 may be so deep that, when polishing the substrate 300, the substrate 300 does not come into contact with the recess 102. That is, any depth that does not enter the polishing region 110 is permitted. When polishing a silicon wafer of 300 mm in diameter using a polishing pad of 743 mm in diameter, any depth up to 26.5 mm is permitted.

The embodiment has been described with reference to concrete examples. However, the present invention is not limited to these concrete examples. For example, although a plurality of recesses 102 acting as cutout parts are arranged, one recess 102 acting as a cutout part can also be constructed. In such a case, rotation of the turn table 520 and movement of the substrate 300 for separation may be synchronized to separate the substrate 300 when the substrate 300 just overlaps with the recess 102.

Also, rotation of the turn table 520 maybe stopped to fix the substrate 300 to the recess 102. In such a case, however, rotation of the top ring 510 is preferably kept to mitigate adsorption power.

If a plurality of recesses 102 acting as cutout parts are arranged, it is preferable to arrange the recesses 102 regularly at a predetermined pitch to produce uniform contact with the substrate. Instead of arranging the recesses 102 regularly at a predetermined pitch, the recesses 102 may also be arranged at random intervals.

Also, the thickness of interlayer dielectric films, and the size, shape, and number of openings that are necessary for semiconductor integrated circuits and various kinds of semiconductor devices may suitably be selected and used.

In addition, all polishing methods, polishing pads, and methods of manufacturing semiconductor devices that are equipped with components of the present invention and suitably modifiable by a person skilled in the art are also included in the scope of the present invention.

Techniques normally used in semiconductor industry, for example, photo-lithography processes and cleaning before or after processing are omitted to simplify a description, but such techniques are naturally included in the scope of the present invention.

Additional advantages and modification will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A polishing method, comprising: polishing a surface to be polished of a target object by using a polishing pad in which a cutout part been formed by cutting out a polishing surface from an outer circumferential end toward an inner part; and after polishing, separating the target object from the polishing pad at a position in contact with the cutout part.
 2. The polishing method according to claim 1, wherein the surface to be polished of the target object is polished at a position not in contact with the cutout part.
 3. The polishing method according to claim 1, wherein the polishing pad in which a plurality of cutout parts been formed regularly along outer circumferential parts of the polishing surface of the polishing pad is used.
 4. The polishing method according to claim 1, wherein the target object is separated from the polishing pad without being moved up to a point outside the outer circumferential end of the polishing surface of the polishing pad.
 5. The polishing method according to claim 1, wherein the target object is separated from the rotating polishing pad.
 6. The polishing method according to claim 1, wherein the target object is separated while rotating.
 7. The polishing method according to claim 6, wherein the target object is separated from the polishing pad after stopping the rotating polishing pad.
 8. A polishing method, comprising: polishing a surface to be polished of a target object by using a polishing pad in which a cutout part been formed by cutting out a polishing surface from an outer circumferential end toward an inner part; after polishing, moving the target object to a position where a contact area between the target object and the polishing pad becomes smaller based on the cutout part formed in the polishing pad; and after moving, separating the target object from the polishing pad.
 9. The polishing method according to claim 8, wherein the target object is separated from the polishing pad without being moved up to a point outside the outer circumferential end of the polishing surface of the polishing pad.
 10. The polishing method according to claim 8, wherein the surface to be polished of the target object is polished at a position not in contact with the cutout part.
 11. The polishing method according to claim 8, wherein the polishing pad in which a plurality of cutout parts been formed regularly along outer circumferential parts of the polishing surface of the polishing pad is used.
 12. A polishing pad, comprising: a polishing surface for polishing a target object; and an outer circumferential side surface in which a plurality of cutout parts been formed from an outer circumferential end of the polishing surface toward an inner part to be cut through from the polishing surface to a back surface of the polishing surface.
 13. The polishing pad according to claim 12, wherein the plurality of cutout parts are formed by a straight line from the outer circumferential end of the polishing surface toward the inner part.
 14. The polishing pad according to claim 13, wherein the plurality of cutout parts have a cutout bottom formed by a straight line.
 15. The polishing pad according to claim 13, wherein the plurality of cutout parts have a cutout bottom formed by a gentle curve.
 16. The polishing pad according to claim 13, wherein the plurality of cutout parts have a cutout bottom formed by a semicircle.
 17. The polishing pad according to claim 12, wherein the plurality of cutout parts are formed by a gentle curve from the outer circumferential end of the polishing surface toward the inner part.
 18. The polishing pad according to claim 12, wherein the plurality of cutout parts are formed by a semicircle formed from the outer circumferential end of the polishing surface toward the inner part.
 19. The polishing pad according to claim 12, wherein a corner between the polishing surface and the side surface of the plurality of cutout parts is formed as a curve.
 20. The polishing pad according to claim 12, wherein a corner between the polishing surface and the side surface of the plurality of cutout parts is chamfered by a plane. 